Hard Lesson in Sleep for Teenagers

Within a week of my grandsons’ first year in high school, getting enough sleep had already become an issue.

Their concerned mother questioned whether lights out at midnight or 1 a.m. and awakening at 7 or 7:30 a.m. to get to school on time provided enough sleep for 14-year-olds to navigate a demanding school day.

The boys, of course, said “yes,” especially since they could “catch up” by sleeping late on weekends. But the professional literature on the sleep needs of adolescents says otherwise.

Few Americans these days get the hours of sleep optimal for their age, but experts agree that teenagers are more likely to fall short than anyone else.

With the profusion of personal electronics, the current percentage is believed to be even worse. A study in Fairfax, Va., found that only 6 percent of children in the 10th grade and only 3 percent in the 12th grade get the recommended amount of sleep. Two in three teens were found to be severely sleep-deprived, losing two or more hours of sleep every night. The causes can be biological, behavioral or environmental. And the effect on the well-being of adolescents — on their health and academic potential — can be profound, according to a policy statement issued in August by the American Academy of Pediatrics.

“Sleep is not optional. It’s a health imperative, like eating, breathing and physical activity,” Dr. Judith A. Owens, the statement’s lead author, said in an interview. “This is a huge issue for adolescents.”

“Lack of sleep can be fatal,” she said. “The level of impairment associated with sleep-deprived driving is equivalent to driving drunk. Would you let a kid drive who just consumed three or four beers? Well, guess what — kids do that every day.”

She recommends that parents make getting enough sleep a condition for permission to drive.

School start times don’t help the situation. In a 2008 study in Virginia Beach, where classes began at 7:20 to 7:25 a.m., the crash rate for 16- to 18-year-olds was 41 percent higher than in adjacent Chesapeake, Va., where school started at 8:40 to 8:45. The lead author of the study, Dr. Robert Vorona of Eastern Virginia Medical School in Norfolk, suggested that starting the school day later could result in less sleep deprivation and more alert drivers.

Insufficient sleep also impairs judgment, decision-making skills and the ability to curb impulses, which are “in a critical stage of development in adolescence,” Dr. Owens said.

“When the students were more alert, they were able to get their work done faster and thus get to bed earlier,” Dr. Owens said. “It takes a sleepy student five hours to do three hours of homework.”

Sleep deprivation can also have a negative effect on mood. Inadequate sleep raises the risk of depression, and sleeping less than eight hours a night has been linked to a nearly threefold increased risk of suicide attempts, after other potential causes are accounted for. The risk of obesity is also increased by sleep deprivation. A study in 2002 estimated that for each hour of sleep lost, the odds of an adolescent’s being obese rose by 80 percent.

Pediatricians, parents and schools need to pay much more attention to the sleep needs of adolescents than they now do. When children reach puberty, a shift in circadian rhythm makes it harder for them to fall asleep early enough to get the requisite number of hours and still make it to school on time.

A teenager’s sleep-wake cycle can shift as much as two hours, making it difficult to fall asleep before 11 p.m. If school starts at 8 or 8:30 (and many start an hour earlier), it’s not possible to get enough sleep. Based on biological sleep needs, a teenager who goes to sleep at 11 p.m. (ha!) should be getting up around 8 a.m.

Middle-school and high school teachers commonly say many students are half asleep or fully asleep during the day’s first period.

Adding to the adolescent shift in circadian rhythm are myriad electronic distractions that cut further into sleep time, like smartphones, iPods, computers and televisions. A stream of text messages, tweets, and postings on Facebook and Instagram keep many awake long into the night. Just the light from a screen can suppress melatonin, the hormone in the brain that signals sleep.

Parents should consider instituting an electronic curfew and perhaps even forbid sleep-distracting devices in the bedroom, Dr. Owens said. Although my grandsons, among many others, use a smartphone as an alarm clock, a real clock that doesn’t have Twitter could easily replace it.

Beyond the bedroom, many teenagers lead overscheduled lives that can lead to short nights. Sports, clubs, volunteer work and paid employment can cut seriously into the time they need for schoolwork and result in delayed bedtimes.

Parental pressure to do well in school can also be a factor. For example, a 2005 study of more than 1,400 adolescents in South Korea, where great emphasis is placed on academic success, found that they averaged 4.9 hours of sleep a night.

Also at risk are many teenagers from low-income and minority families, where overcrowding, excessive noise and safety concerns can make it difficult to get enough restful sleep, the academy statement said.

Trying to compensate for sleep deprivation on weekends can further compromise an adolescent’s sleep-wake cycle by inducing permanent jet lag. Sleeping late on weekends shifts their internal clock, making it even harder to get to sleep Sunday night and wake up on time for school Monday morning.

A version of this article appears in print on 10/21/2014, on page D5 of the NewYork edition with the headline: Hard Lesson in Sleep for Teenagers.